External memory mediums or devices electrically connectable to the personal computer, e.g., a memory card, a hard disk drive, etc. are used to increase the storage capacity of the personal computer. The storage capacity of these devices varies. The memory capacity of a memory card is determined and limited by the number of memory elements incorporated therein and the memory capacity of each individual memory element. As a consequence, when a memory card is used for applications requiring a large memory capacity, the memory elements must each have a large memory capacity.
However, because memory cards are designed to be compact, the number and capacity of the memory elements incorporated therein is restricted. In view of the limited memory capacity of a memory card, in some applications, it may be desirable to use the hard disk drive as an external storage device due to its greater memory capacity. In addition to the limited capacity, memory cards are generally expensive due to the cost of the memory elements incorporated therein.
In the Japanese market, for example, a typical memory card, for example, a Static Random Access Memory ("SRAM") type memory card with a 1 MB to 2 MB memory capacity costs about 20,000 to 30,000 yen. Further, a memory card with a 10 MB to 20 MB memory capacity (requiring memory elements of greater memory capacity, such as a flash memory) costs about 200,000 to 300,000 yen. In contrast thereto, a hard disk drive costs about 80,000 yen for a memory capacity of 80 MB, about 100,000 yen for a memory capacity of 100 MB, and about 150,000 yen for a memory capacity of 200 MB.
Therefore, in view of the comparison between memory capacity and price, it may be desirable to use the hard disk drive rather than a memory card in certain applications because hard disk drives have a larger memory capacity than memory cards and are also less expensive.
Because the hard disk drive is larger than the memory card, it is difficult to load it into a compact personal computer, in particular, into a notebook computer. As a consequence, most compact computers are designed to have a memory card insertion slot or a connector for a memory card so that they may use a memory card as an external memory medium. In order to connect a hard disk drive to a computer designed as described above, a new connector is needed.